Internal combustion engine



NOV. M, 1939.

C. BREBECK INTERNAL COMBUSTION ENGINE Filed April 18, 1938 3nnentorCinornegs 1 Patented Nov. 14, 1939 I UNITED STATES PATENT OFF ICEINTERNAL COMBUSTION ENGINE Charles Brebeck, Herkimer, N. Y. ApplicationApril 18, 1938. Serial No. 202,725

5 Claims.

This invention pertains to internal combustion engines and moreparticularly to engines of the two .cycle type.

In any internal combustion engine cylinder, injurious temperaturestresses may be caused by injudicious distribution of metal,particularly atslightest distortion of the cylinder affects such anengine seriously, making starting difiicult and causing impairment ofoperating emciency. For

these reasons it is important, in the case of small one-piece cylindersto produce a symmetrical design, at vleast as far as the combustionchamber and the adjacent parts are concerned.

It has been customary among miniature engine designers'to follow designsof larger engines. these designs the cylinders are secured at theirlower ends to the crank cases. Ports and transfer passages are formed inmembers either cast,

welded, brazed, soldered, or clamped onto thecylinder barrel. Thesemethods of forming ports and passages set up stresses which causecylinder distortion and unevenness of wall thickness.

The use of cast iron for small engines is unsatisfactory because ofcasting difficulties. The location of a portion of the firing chamberwithin the crank case may result in undersirably high crank casetemperatures, and .in localized' hot spots which cause cylinder andcrank case distortion. Where aluminum or aluminum alloy'crank cases areused with iron or steel cylinders the unequal rates of expansion of thetwo metals may cause separation between the cylinder and crank case.,This may result in exhaust gases entering the crank case and causing anexplosion; or in gas charges seeping out of the exhaust port and in anyevent invites corrosion of the metals where they overlap. The parts mayeven be corroded in such a way as to cause seizure between the cylinderand crank case, and to prevent disassembly without breakage, especiallywhere, as in miniature engines, the metal sections are thin.

I have found after intensive study of the subject that for the abovereasons practices followed in making large engines cannot be followed inmaking miniature engines, and hence that factors which were relativelyunimportant in large engines become highly important in miniaturedesigns, and constitute the difference between success and failure inmaking engines of the latter type.

Accordingly the main object of my invention is to produce an internalcombustion engine in 5 which the heat transfer surfaces aresymmetrically arranged; in which maximum strength of parts may beobtained in parts of small section, and to generally modify and improvethe structure and operation of engines of the two-cycle 10 type.

Other objects and advantages will appear from the followingspecification when read in" connection with the accompanying drawing inwhich:

Figure 1 is a vertical axial section of one form of internal combustionengine embodying the present invention; and

Figure 21s a section on line 2-2 of Fig. 1 illustrating the heattransfer conditions as they 20 are approximated in engines embodying theinvention.

In the drawing, I represents the cylinder, which is preferablymanufactured by machining from a solid bar of steel. This method ofmanufac- 25 ture makes it possible to produce a cylinder wall of thinuniform section throughout, and to obtain symmetry and'strength whichcannot be attained with cast metal, particularly where the parts aresmall. Fins 3 are formed on the cylinder to aid 30 in dissipating heattherefrom to the surrounding air, and a tapped hole t is provided for aspark plug (not shown). From the lower half of the cylinder and integralwith it extends a .peripheral mounting flange 5, which is in a plane 35perpendicular to the axis of the cylinder I.

I locate the exhaust port 6 above the flange 5,. and hence, above thetop of the crank case extension so that exhaust gases do not come intocontact with the crank case as they do in other 40 engines of similardesign. This exhaust port,. being in the part of the cylinder outsidethe crank 'case extension, is in close proximity to the cooling havingthe exhaust port 8 above the mounting flange Band, therefore, the firingchamber entirely above the flange, a greater portion of the cylinder isexternal tovthe crank case. 'Hence, 55

I am enabled to have more space covered by cooling'flns 3 on thecylinder than can be covered on a cylinder of the same size where theexhaust port is below the mounting flange.

The mounting flange 5 may be ground to fit closely on the upper surfaceof an extension of the crank case 8 or, as shown in the drawing, suchsurfaces may haveinterposed between them a gasket l5 of suitablematerial, such as asbestos, copper, or the like. The crank case 8 ispreferably made of aluminum or aluminum alloy so that it will be ofminimum weight. The cylinder I flts within the extension of the crankcase so that intake port II is opposite crank case intake passage I, andtransfer port 8 connects with,

channel I ii in the crank case. Transfer port 9 is formed of openings inthe wall of the cylinder and grooves in the under side of flange I, thebottom of thegrooves being above the lower edge of said flange and belowthe top edge of said flange. The plane passing through the top of theflange is, therefore, above the transfer port and below the exhaustport. This brings the tops of the transfer ports Sand the .bottoms ofthe exhaust ports 6 into very close relationship axially (Fig. 1), sothat the baiile I! carried by the head of piston I2 can be made of aminimum height for most eflicient operation.

This relation of the ports 6 and 9 makes it possible to produce, ifdesired, both a transfer port and an exhaust port by a single drilling,or equivalent, operation and at the same time gives the transfer portsthe upward inclination indicated in Figs. 1 and 2. This inclinationfunctions to direct the entering gases upwardly into the combustionchamber, thus promoting turbulence in the charge and assisting in therapid and thorough expulsion of the exhaust gases. The piston l2 carriesthe usual piston rings l8. In attaching the cylinder I to the crank case8, the only securing means necessary are capscrews which are passedthrough holes I6 in the mounting flange 5 and into recesses tapped inthe crank case. No clamps, lugs, or other projections are used or arenecessary, and since there are no ports formed in parts attached to thecylinder, each port being merely a plurality of holes in the cylinderwall, the mass of metal of the cylinder is evenly distributed and nodistortion is caused by hot spots.

In a miniature light weight engine, the lateral thrust of the piston maybe sufllcient to bend the cylinder slightly, and thus to lead tobreakage. When, e. g., the crank I! is horizontal, the lateral thrust ofthe piston l2 will be greatest. As

shown in dotted lines in Figure 1, when the crank is horizontal, thepiston is in such a position that its wrist pin It will be insubstantial alignment with the mounting flange I. The cylinder is thusstrengthened, and'indeed supported, at the point of its maximum lateralstress.

Referring to Figure 2, I shall now describe the eflect of heat on theexpansion of the metal of the improved cylinder. When a mass of metal ina particular portion of a cylinder is heated, it expands a definiteamount. Unless this .expansion is counteracted by an equal expansion ofthe metal in the area opposite, distortion of the cylinder results. Inorder that expansion on opposite sides of the cylinder may be the same,it is necessary that the masses of metal in all opposite areas be thesame. It is plainly evident that in this cylinder the mass of metalindicated by arrow a is equal to that at a, and similarly b and b, and cand c' represent respectively equal and opposite cylinder masses. In thecase of areas a and d, transfer port 9 comprises sections cut out of thecylinder wall and the flange 5 opposite the exhaust port 6 and theintake port H, the latter being shown only in Figure l.

The mass of metal removed in forming port 8 is substantially equal inamount to that removed in forming both exhaust port 6 and "intake portpressure and a charge will be drawn in. Shortly after piston I2 startsits downward travel the skirt of piston l2 will close intake port H, andthe mixture of gases in crank case 8 will be partially compressed, Nearthe lowermost position of piston l2, exhaust port 6 will begin to openand as the piston moves farther downward, transfer port 8 will beuncovered, admitting the compressed mixture from crank case 8 tocylinder I. This mixture enters the cylinder at a high rate of speed andis directed upwardly along the side of the cylinder by baffle it whichforms a part of the piston head. Scavenging of the burnt gases will takeplace as the piston starts its upward travel and as the fresh chargeenters. The upstroke of piston I2 will compress the gas in cylinder I.The charge will be flred by a conventional ignition system when thepiston is in its uppermost or firing position, and this firing willdrive the piston downward to start another cycle.

It will be obvious from the above description that I have produced anengine of simplicity and emciency, free from bolted, welded or brazedmanifolds or the like, and capable of production in miniature withoutthe failures and defects of prior .art engines of this class. While theinvention has been described as embodied in a miniature engine to whichit is especially applicable, it is to be understood that the novelfeatures may be applied to an engine of any size and that while I haveshown and described only one specific embodiment, it is obvious theinvention may take other forms within the scope of the claims withoutdeparting from the spirit and scope of my invention.

What is claimed is:

1. An internal combustion engine of the crank case compression type,including a cylinder with exhaust ports and a piston enclosing a workingspace; a crank case communicating with said working space through atransfer port in the cylinder and controlled by the piston; a crank anda connectig rod, the parts being so constructed and arranged that thecylinder has an external flange approximately in the plane of the lowerlimit of the working space, saidflange resting on the crank case, thetransfer ports being formed in the lower face of the flange and theexhaust ports being adjacent the upper face of the flange.

2. An internal combustion engine of the crank case compression type,comprising a crank case having a cylinder supporting portion thereon,said portion having an inlet passage to said crank case and a transferpassage; a cylinder having a peripheral mounting flange resting uponsaid portion with a substantial portion of said cylinder dependingwithin said portion, said cylinder having a transfer port on the lowerside or said flange connected to said transfer passage and an exhaustport on the upper side of flange, said ports being substantiallycoaxially related; and a piston movable in said cylinder and enclosingthe working space therein.

3. An internal combustion engine of the crank case compression type,comprising a crank case having a cylinder supporting extension thereon,said extension having an inlet passage to said crank case and a transfere; a cylinder having a peripheral mounting flange resting upon saidextension with a substantial portion of said cylinder depending withinsaid extension, said cylinder containing a plurality of transfer portsbelow said flange and communieating with said transfer and a pluralityof exhaust ports above said flange, said exhaust ports beingsubstantially coaxially related to corresponding ones of said transferports; and a piston movable in said cylinder and enclosing the workingspace therein.

4. An internal combustion engine of the twocycle type comprising a crankcase including an open-endedextsnsionhavinganinletportand a transferpassage: a cylinder having a peripheral mounting flange resting on saidextension with a substantial portion of the cylinder de- Pending withinsaid extension. said cylinder containing at least one transfer portformed in the bottom face of said flange and inclined to the axis of thecylinder, said port connecting said cylinder to said transfer e, andsaid cylinder having at least one exhaust port formed therein at theupper face of said flange and substantially coaxial with said transferport; and

a piston with a bailie thereon movable in said.

cylinder.

case having a cylinder supporting extension; a cylinder carried by saidextension and having a skirt projecting within said extension; and amounting flange on the cylinder substantially midway between thecylinder ends and resting on said crank case extension, said cylinderhaving an exhaust port above the flange in a position to be isolatedfrom the crank case by said flange, and atransfer port at the lower faceof said flange inclined to the cylinder axis and substantiaily coaxialiyrelated to the exhaust CHARLES

